Maildir folders, which are located in a directory which has sub-directories named tmp, new, and cur. Each of these directories may contain files with names which are a combination of a numeric timestamp and some status flags.

Mail::Box::Netzwert

This folder type was especially developed for Netzwert AG, optimized to run on a cluster of servers with folders on NFS. The code is not publicly available (yet).

You have opened the folder read-only --which is the default set by new(access)--, made modifications, and now want to close it. Set close(force) if you want to overrule the access mode, or close the folder with close(write) set to NEVER.

The folder must be opened with write access via new(access), otherwise removing it will be refused. So, you may have write-access according to the operating system, but that will not automatically mean that this delete method permits you to. The reverse remark is valid as well.

According to the RFCs, message-ids need to contain a unique random part, then an @, and then a domain name. This is made to avoid the creation of two messages with the same id. The warning emerges when the @ is missing from the string.

Fatal error: the specific package (or one of its superclasses) does not implement this method where it should. This message means that some other related classes do implement this method however the class at hand does not. Probably you should investigate this and probably inform the author of the package.